Recently there has been a trend in replacing conventional incandescent light bulbs with LED. For example, traffic control signals and automobile brake lights are often manufactured using LEDs. The replacement of conventional incandescent light bulbs with one or more LEDs is desirable because incandescent bulbs are inefficient relative to LEDs, e.g., in terms of energy use and longevity.
While it is desirable to replace incandescent light bulbs with LEDs, there are some lighting fixtures, however, where replacement is difficult because of the operating conditions. For example, in a spot lamp type application, where the light is recessed into a can, heat management is critical.
FIG. 1 illustrates a conventional PAR type incandescent lamp 10 recessed into a can 12. The can 12 is surrounded by insulation 14. A standard PAR incandescent type lamp emits most of its light in the infrared region, i.e., light with λ>650 nm, illustrated as arrows 16. Thus, along with light in the visible region, lamp 10 also emits heat.
LEDs, on the other hand, are designed to emit light at specific wavelengths. LED's that are designed to emit light in the visible spectrum emit no infrared radiation, but generate a significant amount of heat, e.g., approximately 80–90% of the input energy received by the LED is converted to heat, with the remainder converted to light. Accordingly, the heat that is generated by the LED must be dissipated. Unfortunately, in applications such as the recessed lighting fixture shown in FIG. 1, there is little or no air flow, making dissipation of the heat problematic.
Thus, what is needed is a LED lamp that can efficiently dissipate heat even when used in applications with little or no air flow.